Line a 9" brownie pan (or 8" brownie pan for thicker fudge) with parchment paper.
In a large bowl, stir together the popcorn, oats, and salt.
In a large microwave-safe bowl, add the chocolate and peanut butter. Microwave at 30-second intervals, stirring between each one, until melted. Whisk in the protein powder one scoop at a time (it should look like frosting). Whisk in the almond milk and stevia extract.
Dump the popcorn mixture into the chocolate/PB mixture and fold together. Scoop into the prepared pan and flatten it out (I used a pastry roller). Refrigerate for 2+ hours to firm up, then slice with a sharp knife. Serve and enjoy!